withdrawing towards its centre of origin from a former wider range. Such an eventuality, as we have seen, has actually taken place in a great number of instances. It is not only in the British Islands that we perceive the influence of the Lusitanian element. Scandinavia, Russia--indeed almost every part of Europe--can boast of some migrants which have originated in South-western Europe or on the mysterious lands which lay beyond it. As a rule, however, we notice a marked decrease of Lusitanian species as we travel eastward from Western Europe. Nevertheless, certain forms have travelled far beyond the confines of our continent, and we certainly meet with them in Asia and Northern Africa. It is remarkable that we are apt to mistake sometimes for Lusitanian migrants species which are of Oriental origin. In a previous paper I classed such animals which had apparently originated in South-western Europe, but had really come from Asia by a circuitous southern route, with the Lusitanians. However, there is really no reason why the two should not be kept apart, provided we can discriminate between the pseudo-Lusitanians and the true ones. I have already indicated in the last chapter how these pseudo-Lusitanian migrants originated. Supposing an Oriental species had left Asia for Europe in miocene times, it would on its arrival in Greece have had to decide between two courses. It could either advance into the newly-formed Alpine peninsula and there remain, or at once push on westward into Southern Italy, Sicily, and Tunis, by means of the old land-connections, and thence into Southern Spain. The Atlantic communicated at that time with the Mediterranean across the valley of the Guadalquivir; but that connection ceased to exist towards the end of the Miocene Epoch, when the Oriental migrants were free to ramble through Spain and the whole of the North European plain. I have indicated on a previous occasion (_a_, p. 484) that the earliest members of the Red Deer migration, which have left their traces in the caves of Malta, and whose descendants still live in Corsica, Sardinia, and North Africa, may have found their way to Northern Europe in this manner. Many other Asiatic mammals probably reached the British Islands in a similar way.